What's the max size to which the BG grow in your pond? Are your BG pure coppernose?
Also, have you had more ice than usual this year? I noticed that Greg Grimes, who's also in GA, mentioned that he'd seen more ice this year than any other he could recall. The whitish livers could be due to fat deposition, which can be seen in several abnormal nutritional situations; the ulcers can definitely be due to extreme metabolic stress in other animals including humans, though I don't know specifically if this also occurs in fish.
I wonder if it could have been too cold this winter for a pure bred, extreme southern coppernose variant, if this is indeed what's in your pond. It's hard to imagine what else might be affecting so many BG at one time, and sparing the LMB and BC.
